Fig 2: Exploratory analysis of treatment interaction P value as a categorical variable split on probe mRNA expression of 3,669 gene probes in the Herceptin Adjuvant cDNA-mediated annealing, selection, extension, and ligation cohort that have zero expected expression in normal breast tissue. The y-axis shows the -log10 interaction P value where, in this example, C8A is 3.63 × 105. The x-axis shows the log2 fold change where the P value represents the expression difference between the log-mRNA expression for the 25th and 75th percentiles. The negative fold change indicates a hazard ratio < 1.0 or that high expression predicts benefit from trastuzumab. For C8A mRNA expression, the difference between the 25th and 75th percentile was -1.54.

Fig 3: C8A mRNA expression in the Herceptin Adjuvant cDNA-mediated annealing, selection, extension, and ligation cohort split on the cohort mean. The mRNA expression profile suggests that for approximately 70% of the human epidermal growth factor 2–positive cohort, C8A mRNA was not expressed, and 30% had high expression of C8A mRNA. SD, standard deviation.

Fig 4: GSEA histogram comparing Herceptin Adjuvant cDNA-mediated annealing, selection, extension, and ligation cohort samples by C8A mRNA low- versus high-expression status. The immune gene list from Molecular Signature Database (version 4.0) on the right represents the top 50 enriched immune genes in C8A-low versus C8A-high samples and the top 50 enriched immune genes in C8A-high versus C8A-low samples. A detailed list of enriched genes is provided in the Data Supplement.